For safety reasons, tractors, lawn and garden vehicles, and riding mowers may be provided with some form of rollover protection system, or ROPS, to prevent the vehicle from crushing the operator if it accidentally rolls over. The ROPS should be capable of supporting the forces generated by the weight of the vehicle in the event of a rollover, maintaining free space for the operator to reduce the danger of injury.
If a cab is provided, the ROPS may be built into the cab. If a cab is not provided, the ROPS may consist of a generally U-shaped crossbar located above the head of the operator, and legs connected to the vehicle frame.
The ROPS may be straight tubing, and brackets may be welded to the legs or lower section to connect the ROPS to the vehicle frame. The legs or lower section of the ROPS may be welded in a position perpendicular to the vehicle frame. A ROPS is designed to absorb energy from the weight of the vehicle, and the brackets transfer energy from the ROPS to the vehicle frame.
Some ROPS may be adjustable to change the height of the ROPS in certain situations. For example, U.S. Pat. No. 4,877,265 relates to a ROPS that is easily adjustable between different heights, and U.S. Pat. Nos. 4,949,991; 5,503,430; 5,779,272; 5,839,758; and 7,568,732 relate to ROPS that can be folded from a raised or upright position to a lowered or folded down position.
Some folding ROPS are designed so that an operator can easily move the ROPS from the upright position to the folded down position, and lock it in place without the use of tools. For example, a folding ROPS may use retention pins (e.g., rods, clips or bolts) that are inserted through holes or slots in the upper and lower ROPS, and/or through holes in hinge plates joining the upper and lower ROPS. However, the retention pins may fit too snugly or too loosely in the holes. As a result, if the retention pins are too tight, the operator must use a hammer and punch to loosen and remove the pins. If the retention pins become too loose, especially due to wear of the ROPS system, the gap between the pin and hole allows the ROPS to rattle during use.
A folding ROPS is needed that may be easily folded and locked in a raised or lowered position without tools. A folding ROPS is needed that can isolate the upper ROPS from the lower ROPS without rattling during use. A folding ROPS is needed that uses retention pins that do not become stuck, and that do not become loose.